ABSTRACT

The author describes several thought experiments that are important in modern physics, by which he mean the physical theory and practice that developed explosively from the late 19th century onwards. Some thought experiments provide the basis for rigorous arguments with clear conclusions; others seem to work simply by drawing attention to an important question that otherwise might not have been apparent. While the thought experiments to be discussed here are key turning points in the history of modern physical theory, in several cases their full implications remain to be plumbed. It is an extraordinary fact that most of the decisive thought experiments in 20th-century physics were born from the fertile imagination of one person, Albert Einstein. This forces to ponder the importance of individual creativity in the advancement of science. The Einstein-Podolsky-Rosen (EPR) thought experiment dominates investigations of the foundations of quantum mechanics and plays a defining role in quantum information theory.